ag2ai/faststream ? reverse-engineered prompt

Build me a Python library for async event driven services that makes it really easy to write message consumers and producers without a lot of boilerplate.

I want one simple API that works with a few common brokers like Kafka, RabbitMQ, NATS, Redis, and MQTT, and lets me define handlers with decorators. It should handle parsing and validating incoming messages with type hints, and support both Pydantic style validation and a faster msgspec style option if that’s practical. Please include dependency injection, basic testing helpers with in memory tests, and automatic AsyncAPI documentation generation so people can see what each service listens to and sends.

It should feel friendly for someone building microservices, work well with FastAPI or other HTTP apps, and include a clear example app plus tests. If you need to check current docs for broker clients or AsyncAPI details, look them up online first.